I cannot tell you much about the Stepcraft I have the X-carve XXL. It is great for what I do. It will carve about 30 in 30 in product. It works very well when you get it adjusted. This is a kit you must put together, however there are great instructions on the net. If I were to buy again, I would look around and see what it is out there.
The Shark C NC Machines are very good and they come assembled. I have the smaller version with a a 12 x 12 cut. The X-carve for the price is pretty tough to beat. One other thing, there service is great and their support people are very knowledgeable and willing to help and have great patience in my case. Yes I would buy the same unit again.